Plate for secondary batteries.



nw 0 9 \\\|||l .l l/ Q 1 X l! l l/ V O N D Il!!! III/III E m N .1 n S II n P ,0 f A Rn D.. EM mm L .A W a NBB D.. 0 w d z SYB vd. m, TR l m.MAM MMM /Q @Y R w M. n1 .Rw W .JOL 4,6 Fn w m l MA o Pw L P Br A AUrnrnns'pre'rns,v PATENT OFFICE.

JAMES HART ROBERTSON, OF NEW YORK, N. Y., ASSIGNOR TO WILLIAM D. ELGER,OF BROOKLYN, NEW YORK.

PLATE FOR SECONDARY BATTERIES.

Ivo. 835,229.

Specification of Letters Patent.

Patented Nov. 6,'19oc.

Application led February 1,1904. Renewed March 3, 1905. Serial No.'248,330.

5 York, State o New York, have invented certain new and usefulImprovements in Plates for Secondary Batteries, of which the followingis a specification, reference being had to the accompanying drawings,forming a part hereof.

This invention relates to metallic plates or electrodes for secondarybatteries which, after being formed mechanically, are supjected to anelectrochemical formation in Vwhich the substance of the plates is sotransformedl as to make them capable of serving the intended purpose instorage batteries.

The object of the invention is to increase the desired qualities of sucha plate, and particularly to produce a plate which shall have therequisite strength without undue weight, shall expose a very largesurface to the action of the electrolyte, shall have conductive bodyenough to meet the requirements of use, and in general shall possess inan exceptional degree the qualities necessary for the development oflarge electrically-absorptive capacity.

The invention will be more fully described hereinafter with reference tothe accompanying drawings, in which, for the purpose of explanation, itis illustrated in detail.

In the drawings, Figure 1 is a view in perspective of a platemechanically formed in accordance with the invention.` Fig. 2 is adetail view of a portion of the plate on a largerscale than that ofFig. 1. Fig. 3 is a `detail view, in section, on the plane indicated bytheline 3 3 of Fig. 2. Fig. 4 is a diagramforming the plate. Fig. 5 is aview in elevatlon of a partly-formed cutter which may` be employed inthe production of the plae-- matic view illustrative of the manner Jil"recesses or cuts on opposite sides of the plate registering, so that anopening d is formed through the plate. The cuts or recesses are shallow,but relatively long, so that a finelytapering wall e is formed betweenlthe end portion of the corresponding cuts or recesses -at each side ofthe aperture d. The cuts or recesses may be formed by any suitable`means and are conveniently formed by a tool f, which is representedpartly formed in Fig. 5, such tool consisting of a series of cutters orsaws g upon a common shaft h, a-suflicient number of cutters or sawsbeing employed to form at one operation a range of cuts or recesses c,extending entirely across the plate. The plate is subject to the actionof such a tool first on one side, the depth of the cut being slightlygreater than half the thickness of the plate, and then is subjected tothe action of the tool on the other side in the same manner, therelation of the cutter to the plate in the successive operations beingindicated by dotted lines in Fig. 4. For the purpose of increasing thesurface of the plate for the action of the electrolyte each cutter orsaw is grooved circumferentially, as

indicated in an exaggerated manner at t in Fig. 6, whereby the surfaceof each recess c is minutely subdivided by grooves and ribs lc, therebysubstantially increasing the surface lexposed directly to the action ofthe electrote. y It will be obvious that by the use of such amilling-tool as that indicated the recesses may be quickly formedthroughout the extent of the plate and that while the surface exposed tothe action of the electrolyte in the completed plate is very large,nevertheless the strength of the plate is retained in a suiiicientdegree to make it very durable, while its storage capacity is fullyequal to that of `plates which are much heavier, and the crosssect1on ofmetallic lead or other material is gretenough to carry all of the storedenergy Without increasing unduly the internal resistance. The minutegrooving of the bottom surface of the recesses not only contributes tothe increase of the surface exposed to the action of the electrolyte,but presents the metal so finely divided that the metal is very quicklytransformed into active material when subjected to an electrochemicalbath. The provision of the aperture d facilitates the circulation of theforming-bath as well as of IOO the electrolyte, and thereto-re promotesthe formation of the plate and the processes of charging anddischarging.

When the plate has been formed mechan- 5 ically, as already described,it is subjected to the action of a suitable electrochemical forming-bathfor the purpose of transformingpart of the metal of the plate intoactive material. It is obvious that such forming-bath may be of anysuitable character. If it is desired after this electrochemicalformation proc# ess to apply mechanically extra active mazo terial thatshould be afterward added, and it is to be understood that the mereaddition of extra active material after the plates have been formed byan electrochemical process is not a departure from the spirit of thisinvention.

I claim as my invention- A plate for secondary batteries having formedin' each side thereof registering and oppositely-communicating recesses,each being formed in the arc of a circle, whereby finely-tapering partsare formed between the ends ofthe recesses and at each side of a centralapertura-the bottom surface of each recess being longitudinally rooved.

The specification signe and witnessed this 29th day of January, A. D.1904.

JAMES HART ROBERTSON.

ANTHONY N. JESBERA, LUcIUs E. VARNEY.

